The highest day temperature in September 2025 was 70°F. The lowest night temperature was 38°F. The average values for day and night temperatures during September were 57.3°F и 47.7°F respectivly.

The average sea surface temperature in September 2025 for Yellowknife was 58.2°F. The maximum and minimum values were 53.4°F and 64.8°F respectively.

You can expect various weather conditions during September. Be ready for sunny, cloudy or even gloomy days.

Precipitation total in September for Yellowknife is 0.3 in. This value is relatively stable throughout the year.

The average wind speed in September is 9.7 mph. It makes September one of the most windy months of the year for Yellowknife.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Yellowknife in September is 6.5 hours.